Propecia, the 1mg finasteride pill approved by the FDA to treat hair loss, may be far stronger than necessary to prevent hair loss. Numerous studies have shown doses as low as 0.2mg reduce DHT by the same amount as the prescribed 1mg tablet. So is such a high dose necessary to prevent hair loss? Is there a lower risk of side effects by taking a lower dose? In this article we’ll examine what the optimal finasteride dose for hair loss is.

Finasteride inhibits the enzyme 5-alpha reductase, which is what converts testosterone into DHT. No 5-alpha reductase = no DHT.

And in 1997, finasteride was approved by the FDA to treat male pattern hair loss.

Finasteride

But hair loss wasn’t the first medical condition finasteride was approved for. Five years earlier the drug was approved for the treatment of benign prostatic hyperplasia (BPH). The dose approved for BPH – 5mg – was marketed under the name Proscar.

The finasteride dose approved for hair loss was much lower: 1mg. This formulation was given the brand name Propecia.

In the original trials for Propecia, the 1mg dosage was found to result in a “significant net increase in hair count” after 12 months. As far as side effects were concerned, the trials found:

“Finasteride 1mg/d in the treatment of [male pattern baldness] has been well tolerated, with a low incidence of drug-related adverse effects, chiefly in the area of sexual adverse events.”

Since the initial approval of Propecia, the 1mg dosage has been challenged. This is due, in part, to increased reports of side effects. What’s more, some studies have shown that lower doses of finasteride have just the same effect on DHT levels.

Finasteride dose response

Even before Propecia and Proscar were approved, there was already strong evidence that DHT inhibition did not vary much in response to finasteride dose.

Part 1 of the study tested daily doses of 25, 50, and 100 mg for 11 days. Part 2 of the study tested doses of 0.04, 0.12, 0.2, and 1.0 mg for 14 days. These tests revealed:

“Results from part 1 showed a significant reduction in dihydrotestosterone (DHT) at all doses and a significant increase in both testosterone (T) and delta 4-androstenedione at the 50- and 100-mg doses. […] Results from part 2 again showed significant reduction in DHT at all doses. […] The DHT metabolites and androstanediol glucuronide and androsterone glucuronide were significantly reduced at all doses. […] In conclusion, finasteride is well tolerated by normal volunteers and results in significant suppression of serum DHT at all doses tested.”

What these trials did find, however, was that the length of time before maximum DHT inhibition was achieved did vary according to dose. For example, a high dose of finasteride would lead to a significant reduction in serum DHT levels almost immediately. Smaller doses led to a cumulative decrease in serum DHT, eventually resulting in similar DHT levels to higher doses:

“After treatment, DHT levels decreased in each active treatment group, but the rate of decrease was dose dependent. No significant change occurred in the placebo group. Maximum suppression occurred rapidly in the 1.0 and 0.2 mg groups and continued throughout the treatment period. In the 0.12 and 0.04 mg groups suppression required increasingly longer to achieve and may not have been complete after 14 days. […] Maximum suppression of DHT occurs after a single dose of 1 mg/day, but equivalent suppression can be achieved in a dose-dependent fashion with lower doses after repeated administration.”

What this research suggests is that doses of finasteride as low as 0.04mg have the same DHT-reducing effects as 1mg or higher – it just takes a little longer to reach the same levels.

So if DHT is suppressed equally by 0.04mg finasteride as the prescribed 1mg Propecia tablet, it could very well be equally as effective at stopping hair loss progression as well.

Subsequent studies revealed similar results. For example, this study recorded the following reductions in scalp DHT levels with varying doses of finasteride:

Reduction of scalp DHT levels according to finasteride dose

Could a lower dose reduce side effects?

These studies raise the question of why Propecia is a 1mg finasteride tablet when a smaller dose would have the same effect. And this question has been raised in another article in a medical journal:

“As seen in Figure 1, the percent change of DHT for placebo and 0.01-mg Propecia were identical and essentially 0 within a reasonable statistical estimate. The change dropped to 60% for a 0.05-mg dose and stayed that way for all doses up to 5 mg. Thus, a 20 times smaller dose than that recommended had the same effect on the DHT. A similar dose dependence was seen for the serum DHT level (Figure 2); the effect was no different with doses above 0.2 mg.”

It seems clear from the trials cited previously that lower doses of finasteride have more or less the same effect on DHT.

“Thus, the fact that the dose has been established by the manufacturer at a level far higher than the level measured as necessary for the inhibition of the conversion of testosterone to DHT has not been reported publicly. Vastly lower doses would likely reduce the chance of side effects.”

However, this seems unlikely in practice.

If a 0.5mg dose of finasteride, say, reduces DHT levels by the same amount as 1mg, then side effects are just as likely to occur. After all, a reduction in DHT is precisely what causes side effects in the first place!

In other words, if two different finasteride doses lower DHT by the same amount, they’ll both cause the same side effects.

Very low doses of finasteride – less than 0.2mg – are likely to reduce the occurrence of side effects in those susceptible. But this is only because such a small dose would not significantly reduce DHT. So whilst side effects would be reduced, so would the benefits for your hair. Because the effectiveness of finasteride lies in its ability to reduce DHT levels, the incidence of side effects is likely to be directly proportional to the benefits for hair maintenance and regrowth.

Is it necessary to take finasteride every day?

So if reducing the dosage has little impact on results or side effects, what about reducing the frequency with which finasteride is taken?

The half-life of a drug is the amount of time it takes for the body to remove half of the dose. For finasteride, this is around five to seven hours. So, if you’re taking finasteride every 24 hours, all traces of the drug are likely to be removed long before your next dose.

“The terminal elimination half-life (t1/2z) is 4.7 to 7.1 hours; but despite this, slow accumulation occurs with multiple doses. […] A single dose of finasteride suppresses serum DHT levels for up to 4 days, longer than would be expected from the serum terminal elimination half-life (t1/2z) of the drug: this is probably due to the high affinity that finasteride has for the 5 alpha-reductase enzyme.”

It’s important to note that the dosage discussed in this article is 5mg. However, this suggests that taking Propecia every other day – perhaps even every third or fourth day – will have the same effect as taking it every day.

A potential drawback of administering finasteride this way, though, is fluctuations in hormone levels. Taking finasteride every day is more likely to keep levels of DHT and other hormones more stable. If DHT is allowed to creep up for up to four days after medication, these fluctuations could increase the likelihood of side effects.

The best finasteride dose for hair loss

The prescribed Propecia dosage of 1mg finasteride every day undoubtedly works for hair loss.

Increasing this dose is not likely to have an appreciable effect on hair. But nor is it likely to increase the risk of side effects either.

Similarly, evidence suggests that decreasing the dose – even to as low as 0.2mg per day – won’t be any less effective for hair loss. But it won’t reduce the likelihood of side effects either.

You could even get away with taking Propecia every other day – possibly even every four days. As shown, this is not likely to have a significant effect on DHT levels.

But the approved dose for hair loss – Propecia – has been trialled and tested extensively.

In theory, lower doses would be just as effective. But a lower dose does not necessarily reduce the chance of side effects.

Research the hair loss industry chooses to ignore

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I would be very careful because you are diabetic. You already have a predisposition to erectile dysfunction from diabetes. Taking propecia will put you at significant risk to have irreversible sexual dysfunction.

So, although by increasing the dose you won’t necessarily reach a significantly higher level of increased suppression in DHT levels, maybe dosing 1mg in the morning and 0.25mg for instance in the evening, will suppress the levels more consistently and potentially lead to quicker results….? This would make sense to me. To you?

From one of the trials above: “A single dose of finasteride suppresses serum DHT levels for up to 4 days”

Of course, DHT levels do gradually increase over these 4 days, but I doubt this fluctuation is especially dramatic during just one day. I doubt you’d notice any difference in results by splitting your dosage up like this.

Great article. I have been using finasteride to prevent hair loss for the last 20 years with good results. I have always used proscar(5mg)because it is much cheaper. I also use slightly lower doses than that prescribed by taking small bites each day out of the 5 mg tab so that one pill typically lasts me 6-7 days, or about 0.75 mg/day on average. The proscar pills are soft and easy to nibble off of. And while these bites can lead to inconsistent doses from day to day, the dosing is consistent week to week. I have had good results and am reassured by this article.

After reading this article, I plan on stretching each 5 mg tab out to maybe ten days(0.5 mg/day)

This is a good, factual and we’ll balanced article. However, findings and understanding of how Finasteride actually works have changed in recent years, even from the original manufacturer’s understanding.

Published analysis shows that it DOES NOT act as an antagonist as thought but actually ACTS as a mechanism-based inactivator of the 5a Reductase Enzyme. This reaction throws off a bisubstrate analogue in which dihydrofinasteride is covalently bound to NADP+.

Subsequently through competitive activity Finasteride metabolates impact on the AKR1D1 enzyme (5b reductase) and in a dose dependant manner that is higher than the dose dependent value on the 5a Reductase.

So Finasteride blocks 5a synthesis and all the effects are as you say well documented.

Research now shows that in a dose dependent manner it blocks the 5b synthesis. Now this process has significant effects on sexual behaviour and brain activity, not least through 5b progesterone synthesis and it’s metabolates.

Personally I began on 1mg for 2 years and had all the side effects recorded: reduced watery ejaculate, reduced desire, reduced feelings, no dreams, dry eyes, etc (note 5b very important here). These reduced after 13 months, exactly as others see and was shown in tests. Hair grew remarkably, by as much as 30% by year 2, even to a full fringe (little benefit at 6 months, just steady increase to year end then big gain in 2nd year).

So I accepted side effects.

In year 3 Doctor gave me the full 5B report and I dropped to 0.5mg per day.

It’s now Year 6.

I have NO side effects at all and actually gained even more hair since year 2. The biggest changes have been in eyes (dryness eliminated and prescription actually improved from R-2.75 L-3.75 to R-2.25 L-3.50), sexual desire and mood (including regular dreams). Erectile performance and orgasm actually very good, would suggest higher than before start on Fin, driven by +12% Testosterone and +10% Estradiol compared to pre-Fin start (Doctor has done pre and post blood tests and one every 12 months).

I can only speak from.experience.
The article on Finasterides true working methods and impact in 5B Reductase can be found here….then Google the impact of 5B suppression and you will recognise I’m sure the effects…

I have been taking Propecia (1 mg) for 17 years. For many years (to save money) my doctor would give me a prescription for proscar (5 mg), which was covered by my insurance, and I would cut these tablets into quarters (and take 1.25 mg daily).

Recently (at the age of 66) I have noticed some hair loss on my forehead (thinning out).

Is it safe or has it been studied to take Propecia and another DHT reducer (such as FINASAFE) together, and if so might this help reduce my hair thinning?

Hello Henry
Just wondering for exactly how many years you have been using quarter of Proscar (1.25 mg) and if you found that method to be as effective as when you were taking Propecia?
I’ve always taken quarter Proscar but would be interested in knowing if the single dose, complete tablet Propecia is better.

My understanding is that the sexual side effects are very much psychosomatic … Study participants are told what they might experience and then they are hyper-aware of their libido, etc. What does everyone else think?

hello there i have been experiencing hair loss and am 22 years old so i wanted to ask whether i should take finasteride ,as my doctor gave me a 1mg dosage but still i am a bit skeptical about the side effects one of them being impotency as researched by me, which draws more attention than any other side effect it may have so is it really advisable to take this drug or no as i am willing to take it but need some one to give me the required confidence to take it by explaining the disadvantages or merits and the ideal dosage which is safe for routine consumption although i have been given a 2 months prescription but please let me know. thank you.

I am 42 year old having diabites from 2 years my post lunch level are 165.
Just had hairtransplant my docter advised me to take finestride 1mg mimium for 2 months.
I am afraid of having it he said for 2 months its ok

hi
i am 30 year old and i have no any health problem like blood sugar , heart, blood pressure etc. last month i was transplanted my hair , after that my doctor suggestion me finasteride 1 mg and minioxidil 10% upto 6 months.He tell me the side effect of finasteride ,so he suggestion me to take 2 months countiue finasteride 1mg /day.After complete 2 months doses stop it for 15 days and again countiue it 2 months vice-versa upto 6 months. He told the side effect of finasteride is if we use it countiue. If we break it for few days and again start then the side effect might be not. And the body is recover it.

I cut each of my 100mg Propecia tablets into eight pieces and then take the residue as day one – giving me nine days’ dosage for each 100mg tablet. I have lost no hair over the nine years I have been doing this. It’s clear that a 1 mg daily dose is far greater than that which is needed to stop hair loss. Reducing dosage has stopped brain fuzz and other side effects. I do however have reduced libido though, but this could be due to age (67). I hope this is helpful.